This invention relates to a method for measuring sound absorption power of a theater (hall) chair with a human being seated thereon and a sound absorption dummy used for this method and, more particularly, to the method and dummy which can measure sound absorption capacity of a hall chair in such a state easily and accurately.
A sound absorption characteristic of a chair in a theater or auditorium (hereinafter referred to as xe2x80x9ctheater chairxe2x80x9d) is a very important factor in the acoustic designing of a theater. It has generally been customary in the past to measure a sound absorption characteristic of a hall chair per se in a state wherein a human being is not seated on the chair. The sound absorption characteristic of a hall chair should however be measured in a state wherein a human being is seated on the chair in question.
It has recently been proposed to provide a theater chair with a constant sound absorption power intended to enable an acoustic characteristic of a hall to remain unchanged between a state wherein a human being is seated on the hall chair and a state wherein he is not seated thereon (e.g., as described in the specification and drawings of Japanese Utility Model Application No. Hei 4-45924 filed by the assignee of the present invention). In designing such a hall chair, it is necessary to measure not only the sound absorption characteristics during an unseated state but also those during a seated state.
In a case where a sound absorption characteristic of a hall chair during a seated state is to be measured, a measurement is made under the condition that a human being is actually seated on the hall chair.
The method according to which the sound absorption characteristic is measured with a human being seated on the theater chair however has the following inconveniences:
1. Reliability and reproducability of a measured value are not adequate. Since the posture of the person seated on the hall chair differs from person to person and since presence of a human being affects temperature and humidity of the chamber (hall) in which the measurement is made, these factors cause measurement errors. Further, movement and posture of a human being and the clothing he wears during the measurement also affect the measurement very much.
2. It is difficult to compare results of the plural measurements with each other for the reasons described above in 1.
3. The measurement is an unpleasant experience for the human being seated on the hall chair and this causes the inconvenience described above in 1.
4. It is a troublesome task to collect ten to twenty persons to be measured at one time.
It is, therefore, an object of the invention to provide a method for measuring a sound absorption capacity capable of easily and accurately measuring a sound absorption capacity of a hall chair with a human being seated thereon and provide also a sound absorption dummy used for this method.
A method for measuring a sound absorption power of a theater chair with a human being seated thereon achieving the above described object of the invention comprises steps of disposing a chair which is an object of measurement in a measuring environment; disposing a dummy sound absorber in the chair, said dummy sound absorber having a shape in which it is in contact with the chair, a sound absorption power and a chair pressing force in such a manner that the dummy sound absorber simulates a human being seated on the chair; causing changes in the chair which changes are substantially equivalent to the changes in the state of the chair caused when a human being gets seated on the chair and a change in the sound absorption power of the chair caused by seating of the human being thereon; and measuring the sound absorption power of the chair.
A dummy sound absorber used for measuring a sound absorption power of a chair with a human being seated thereon comprises a chair contacting portion having a shape which is substantially equivalent.to the shape of portions of a human being which are in contact with a seat and a back of the chair when the human being is seated on the chair, sound absorption power generation means for generating a sound absorption power which is substantially equivalent to the sound absorption power formed by a human body when the human being wearing clothing is seated on the chair, and pressing force generation means for generating a weight or a force equivalent to the weight for imparting a pressing force which is substantially equivalent to a pressing force imparted by the human body to the seat surface and the back of the chair when the human being is seated on the chair.
According to the invention, measurement is performed by disposing in the chair a dummy sound absorber having a shape in which it is in contact with the chair, a sound absorption power and a chair pressing force in such a manner that the dummy sound absorber simulates a human being seated on the chair and, hence, results of measurement which are substantially equivalent to those of measurement conducted when a human being is seated on the chair can be obtained. Moreover, since the seating condition can be standardized and an immobile posture can be maintained, as compared to a case where a human being is seated on the chair, and since the disposition of the dummy in no way affects temperature and humidity of the measuring environment, data available when a human being is seated under standard conditions can be obtained. As a result, reliability and reproducability of the measurement of the sound absorption power can be maintained. Further, data of chairs of different specifications can be compared with each other with accuracy. Furthermore, since it is not necessary to collect many persons to be measured, the measurement can be made at any time and with great ease.
Further, according to the invention, in designing a theater chair with a constant sound absorption power, difference in the acoustic characteristic of the theater between the seated state and the empty state can be minimized by measuring the sound absorption power in the seated state and that in the empty state and designing the theater chair on the basis of the result of the measurement.
Preferred embodiments of the invention will now be described with reference to the accompanying drawings.